Thermal Radiation
The emission of electromagnetic energy from matter due to thermal agitation of its charged constituent particles.
Governing formula
P = ε σ A T⁴ (Stefan-Boltzmann Law)
SI unit
W
In depth
Unlike conduction and convection, radiation requires no physical medium and can propagate through a vacuum at the speed of light.
Examples in the real world
Sunlight warming the Earth across 150 million kilometers of empty vacuum space.